A phase 3, randomized, open-label, multicenter study evaluating the efficacy and safety of TAR-210 erdafitinib intravesical delivery system versus investigator’s choice of intravesical chemotherapy in participants with high-risk non-muscle-invasive bladder cancer with susceptible FGFR alterations who had received intravesical Bacillus Calmette-Guérin (BCG)

This study is looking for adults aged 18 or older who have been diagnosed with high-risk non-muscle-invasive bladder cancer. This means the cancer is in the inner lining of your bladder and hasn't spread to the muscle, but has a higher chance of coming back.

To join, your cancer must also have a specific genetic change called an FGFR alteration, which can be found by testing your urine or a sample of your cancer tissue. Importantly, you must have already received a previous treatment called Bacillus Calmette-Guérin (BCG) for your bladder cancer. Also, your current cancer needs to have been completely removed and you must either not be able to have, or have decided against, surgery to remove your entire bladder.

If you decide to take part, the study will last about 5 years in total. It starts with a screening phase of up to 60 days to check if you're suitable. After that, you'll enter the treatment phase, which lasts for about 2 years. During this phase, you'll be randomly (like drawing lots) assigned to one of two groups:

* **Group A:** You’ll receive TAR-210, which is a small device placed inside your bladder that releases medicine. * **Group B:** You’ll receive a standard chemotherapy treatment (either Mitomycin or Gemcitabine) given directly into your bladder.

Throughout the study, you'll have regular check-ups. These include blood and urine tests, physical exams, checks of your vital signs (like blood pressure), and reviewing your medical history. After your treatment phase, there's a follow-up phase that can last up to 5 years from when you started treatment, where your health will continue to be monitored.